That conclusion may put to rest intense speculation that Berezovsky, 67, was the victim of a Kremlin-inspired assassination plot. Pathologists still have toxicology and histology tests to perform before making a final report.

The onetime billionaire and erstwhile power broker in Moscow was found dead on the floor of a bathroom at his home in Ascot on Saturday. Family and friends who found him said there was no sign of blood and that a scarf was lying next to his body, according to The Guardian.

He was instrumental in promoting Vladimir Putin to the Russian leadership, but after Putin became president, Berezovsky soured on him and sought to expose alleged misdeeds. The oligarch eventually left Russia and was granted asylum in Britain in 2003.

His death prompted immediate comparisons to the 2006 murder of Alexander Litvinenko, a former KGB officer who was friends with Berezovsky. Litvinenko, also a British emigre and vocal opponent of Putin, was poisoned with radioactive polonium.

But there were strong hints that Berezovsky may have been driven to take his own life after losing a multi-billion dollar legal dispute last year against fellow Russian oligarch Roman Abramovich. A news report last week, just days before his death, said Berezovsky was trying to sell his art collection to pay his creditors.

In an interview with Forbes' Russian edition less than 24 hours before his body was found, Berezovsky sounded a note of resignation, saying that "there is no point in my life. ... I'm 67 years old, and I don't know what I should do from now on."